The Collaborative International Dictionary of English v.0.48:
Tar \Tar\, n. [OE. terre, tarre, AS. teru, teoru; akin to D.
teer, G. teer, theer, Icel. tjara, Sw. tj[aum]ra, Dan.
ti[ae]re, and to E. tree. [root]63. See Tree.]
A thick, black, viscous liquid obtained by the distillation
of wood, coal, etc., and having a varied composition
according to the temperature and material employed in
Coal tar. See in the Vocabulary.
Mineral tar (Min.), a kind of soft native bitumen.
Tar board, a strong quality of millboard made from junk and
old tarred rope. --Knight.
(a) A cold infusion of tar in water, used as a medicine.
(b) The ammoniacal water of gas works.
Wood tar, tar obtained from wood. It is usually obtained by
the distillation of the wood of the pine, spruce, or fir,
and is used in varnishes, cements, and to render ropes,
oakum, etc., impervious to water.